The above code does not display any of the child panels (Column1, Column2 or Column3) unless we change the layout Main Panel from HBox to something else.

This is true even if there is one more component present in between Main Panel and Container with layout different from hbox.

It seems that if any of the component has a layout of HBox then neither its children nor any child of its children is allowed to have a column layout. Is this correct or are we doing something wrong here?